GNU screen color and pine

alpine-mailcolorsgnu-screenncursesterminal

I use GNU screen to run pine mail reader. I use external aspell to do spellchecking for the e-mails I sent. The problem is that when aspell finishes, pine restores the old content of the terminal, but the color is all wrong. The font becomes white instead of black, which looks very bad on the the gray background. After typing something for a while, pine redraws parts of the screen, and that looks ok, but initially it looks very hard to read.

The problem does not exist when pine is run directly, not from within screen. I do not know how to begin the troubleshooting. Any ideas?

Pine version: Alpine 2.00 (LRH 1167 2008-08-23) 
GNU screen version: Screen version 4.00.03 (FAU) 23-Oct-06

Update 11 Dec 2011:
The problem also occurs in some cases when resuming composition with Ctrl+O (no aspell involed).

The following do not help:

Ctrl+L in pine to refesh screen,
adding "altscreen on" in ~/.screenrc
adding "bce on" or "bce off" in ~/.screenrc (I tried both, as I am not sure what the default is)
Starting screen with TERM=xterm-256color screen

Best Answer

I think I have resolved it. phunehehe was right about trying to change the terminal type. However, "TERM=xterm-256color screen" does not work because the TERM variable only tells screen what kind of terminal screen is run in. It does not tell screen to emulate that particular terminal. So, the solution was to include

term "screen-256color"

in ~/.screenrc configuration file. This seemed to solve the problem, but....

Update 12 December 2011: Actually doing the above fixed the color problem, but created another problem: Delete key no longer works in pine. It turned out that the computer on which screen is running lacks "screen-256color" terminfo file, and since it cannot find it, it reverts to the basic vt100 terminal. After trying several term settings, I found that "xterm-color" has neither Delete-key nor color problem. I do not understand why or how it works.

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GNU Screen – Start Session as Non-Root User

This is a known problem, if you ssh as root somewhere and then su to become a normal user:

$ ssh root@server
# su -l anthon
$ screen 
Cannot open your terminal '/dev/pts/3' - please check.

It is e.g. described in these posts from 2005

The solution is to directly login as the user you want the screen session to run as.

terminal – Clear to End of Line Uses Wrong Background Color in Screen

When you send one of the ECMA-48 erase control sequences, whether the erasure uses the current background colour or the default background colour varies amongst different terminal types. (In the terminfo database, there is a capability that allows programs to determine what the terminal that they are talking to will do. It is named bce. The termcap equivalent name is ut.) You are setting the current background colour, and then erasing to the end of the line, expecting the erasure to always use that current colour.

screen is a terminal emulator itself. But unlike most hardware terminals its behaviour in this regard is switchable. By default, background colour erase is switched off, and the control sequence causes erasure with the default colour. One switches it on with the bce command. One sets the default for the bce setting in all new screens with the defbce command.

(I say most, because late model DEC VTs provide DEC Private Mode 117 for switching the behaviour. The default for these terminals was the "new" PC-compatible behaviour of erasing with the current colour, and switching Private Mode 117 off would revert back to the "old" VT-compatible behaviour of erasing with the default colour. DEC VT 52x terminals were switchable like screen, except that the host could do the switching and the default was the "new" behaviour, the opposite of screen's default. These terminals were actually newer than screen, by several years.)

So switch it on. It's as simple as that.

Best Answer

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GNU Screen – Start Session as Non-Root User

terminal – Clear to End of Line Uses Wrong Background Color in Screen

Further reading

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